Safety joint



March 14, 1950 w, CHURCH 2,500,276

SAFETY JOINT Filed Dec. 22, 1945 I i .2 I

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Patented Mar. 14, 1950 UNITED STATES FATENT OFFICE SAFETY JOINT WalterL. Church, Houston, Tex.

Application December 22, 1945, Serial No. 636,898

1 Claim. 1

This invention relates to a safety joint.

An object. of the invention is to provide a safety joint which isspecially adapted for connecting sections of an operating spring of pipeand which may be readily broken and separated in case it becomesnecessary to do so.

The type of joint herein described has been specially designed for usein connecting string of pipe to a packer to be set in a well.

In the production of oil, or other fluids, from a well it is not.uncommon to set a packer in the well and to produce the fluid throughthe string of pipe by means or which the packer is set. It sometimesbecomes desirable to collapse and remove the packer and the settingstring of pipe from the well but in case the packer cannot be removed itis desirable to detach and remove the string of pipe.

In order that the string may be detached the safety jointhereindescribed is incorporated into the string above the packer so thatwhen it is attempted to detach the string from the packer the safetyjoint will, break, and can be unscrewed, more easily than the couplingsconnecting the sections of they string above. This will in,- sure theready removal of the entire operating string from the well in case thepacker becomes stuck and cannot be removed.

It is another object of the invention to provide a safety joint of thecharacter described that will not readily part, or unscrew, while thepacker is being lowered into the well or during the manipulation of thestring during the setting operation but which may be readily unscrewedand detached from the packer mechaanism beneath in case the packerbecomes sanded up or for any reason stuck in the well so that it cannotbe removed.

With the above and other objects in view the invention has particularrelation to certain novel features of construction, arrangement of partsand use, an example of which is given in this specification andillustrated in the accompanying drawings, wherein:

Figure 1 is a side elevation, partly in section, of the safety jointshowing the coupling members connected together.

Figure 2 is a fragmentary side elevation of the pin member and means forcoupling said member to the string of pipe above; and

Figure 3 is a cross-sectional view taken on the line 3-3 of Figure 1.

Referring now more particularly to the drawings wherein like numerals ofreference designumeral i designates an operating string of pipe whichextends to the ground surface.

Screwed onto the lower end of the string there is a tubular reducingbushing 2, threaded onto the lower end of which there is a tubular outernipple 3.

The numeral i designates a tubular pin member whose upper end fitssnugly in the lower end of the nipple 3 and whose lower end is reducedin diameter forming the downwardly facing, external annular shoulder 5,and extending upwardly from this shoulder on opposite, sides are thelongitudinal keyways 6, 6 which extend up the required distance. Abovesaid keyways and countersunk into the enlarged upper end of the pinmember are the annular seals '1, l which extend around said pin memberand form seals with the nipple .i.

The lower end of the nipple is formed with the inwardly extending keys8, '8. which extend into said keyways.

There is a tubular box member S3 which is provided with internal coarsethreads [0 and said box member is internally blank above and beneathsaid threads.

The reduced portion of the pin member is provided with coarse externalthreads I! adapted to mesh with the threads it when the pin member isscrewed home into the box member.

The pin member is externally blank above and beneath the threads H, saidblank portions fitting into the blank portions of the box member whensaid coupling members are screwed together.

Countersunk into the pin member beneath its threads are the annular sealrings [2 which form seals with the box member when the pin member isscrewed home therein. The threads Hi and H, in the present illustration,are left hand threads.

The box member has the slots, as l3, which are formed in the end of thebox member which is adjacent the nipple 3. These slots have thelaterally turned notches, as l3a, at their lower nate the same parts ineach of the figures, the

ends, said notches, in the present illustration, being turned to theleft and thus forming overhanging shoulders, as M, and the adjacent endof the nipple 3 is provided with the extended prongs l5, 15 which extendinto the slots l3 but which are somewhat narrower than said slots, asshown in Figure 1, and which have lateral projections Isa extended intothe notches l3a and forming the shoulders 16 arranged to interlock withthe shoulders I 4. These shoulders are maintained in interlockingrelation by means of a key l1? 3 which is shearable under abnormal,torsional strain.

In assembly the pin member 4 is screwed into the box member 9 to homeposition and the prongs l5 are then moved into the slots l3 and turnedto interengage the shoulders It with shoulders M and the key ll is thencountersunk into the adjacent ends of the nipple and box member, asshown in Figure 1. The nipple 3 is then screwed onto the reducingbushing 2 which is attached to the operating string of pipe I.

A well packer assembly may then be connected onto the threaded lower end[8 of the box member 9 and the packer mechanism let down into the [wellbore to the desired location.

In order to set a type of packer assembly with which the safety joint isdesigned to be used the operating string must be turned to the right soas to release the packer assembly and allow it -to become engaged withthe well casing and the operating string is then lowered to subject thepacker to the weight of the operating string to expand the packer.

The key ii is of sumcient strength to withstand the torsional strain ofthis operation so that the safety joint will not be liable to becomeseparated.

Later if it should be desired to remove the packer from the well anupward pull may be taken on the operating string and the shoulders l6,l4 being engaged the load will be assumed by them and the packerassembly may be removed from the well.

However, if the packer assembly is sanded up or stuck so that it cannotbe removed by a straight pull the operating string of pipe may be turnedto the right and the pin H sheared and the shoulders I S will thenbecome disengaged from the shoulders l4 and upon an upward pull on thestring of pipe the nipple 3 will move upwardly relative to the pinmember 4 until the keys 8 engage the upper ends of the keyways B and theoperating string may then be turned to the right and the threads lldisengaged from the threads l0 and the operating string may then bewithdrawn from the well bore and thus recovered.

The drawings and description are illustrative merely while the broadprinciple of the invention will be defined by the appended claim.

What I claim is:

A safety joint for connecting sections of a string of pipe andcomprising, a tubular nipple, a tubular pin member, one end of which istelescoped into and has a slidable splined connection with the nippleand whose other end is provided with external threads, a box memberhaving internal threads into which said other end of the pin member isthreaded, the end of the box member, adjacent the nipple, being formedwith a slot having a laterally turned notch at its inner end, thusforming an overhanging shoulder and the adjacent end of the nipple beingprovided with an extended prong which extends into said slot and isnarrower than the slot, a lateral projection on said prong which extendsinto said notch and which forms a shoulder, said shoulders beingarranged to interlock to hold the adjacent ends of the nipple and boxmember in contact, frangible means initially locking the nipple and boxmember together against relative rotative movement when the projectionextends into said notch, but which is shearable, under stress, to allowdisengagement of said shoulders to permit relative longitudinal movementof the nipple and box member, and means arranged to prevent completeseparation of the nipple and box member.

WALTER L. CHURCH.

REFERENCES CITED The following references are of record in the file ofthis patent.

UNITED STATES PATENTS Number Name Date 2,049,290 Burns et a1 July 28,1936 2,113,821 Baash Apr. 12, 1938 2,189,697 Baker Feb. 6, 1940

